Our PTO pays for the transportation for each grade level once per year. If third grade takes three field trips then we pay for the most expensive transportation cost for only one of their field trips. Our annual budget for this is $2000 and that covers the transportation for one field trip per grade level K-8. This is the only way we can stay consistently fair to all grade levels.
We budget $5.00 per student, in many cases that covers the cost of admission and the principal budgets the cost of the busses. We may actually look into raising this year to $6 because the cost for everything has climbed so much.
We strive to make our field trips free for families. Our school district budgets some monies to support field trips, but of course there's never enough and the PTO helps to make up the difference. We have introduced an annual fundraiser that's specifically geared to raising money for class needs - for supplies, books, and field trips. Any money raised stays with the class that earned it (though held by the PTO) and can be spent on any reasonable class expense. A significant portion of those monies are spent on supporting field trips.
We still have some one off asks that come to the PTO, but they are generally small amounts in excess of what the district budget and the above class monies can cover. We review each of those as a one-off and individually vote on whether or not the PTO should fund it - but honestly we've never said no. Our teachers work hard to be reasonable in their requests, and our perspective is that supporting these kind of opportunities is a primary reason why we as a PTO exist.
We have one exception to the "reasonable requests" category, in that our oldest elementary class has a special annual trip that is massively expensive (4 times more expensive than any other trip). There's separate fundraising specific to that trip in order to cover those costs, or the parents would have to chip in per student.
My advice would be to look at your budgeting, categorize what you are spending money on and look at how it aligns to your goals as a PTO. You could even do a quick survey of the teachers and parents (free accounts on SurveyMonkey work great) to get a group consensus on where the PTO (and its spending) has and should have the greatest impact. Then you have something solid you can use as a basis for budget alignment decisions.
We pay for 1 field trip each year and the annual author visit. It is a 4th grade all day community learning experience. If we did not have enough funds to cover, then we would not support these extras. The school would have to decide if they wanted to support these items or cancel them.
Our PTO pays $100/student towards field trips. Teachers sometimes ask parents to send $1-2 in to cover the difference. I know of several teachers that cover it out of their own pocket (this is above and beyond in my eyes). I always think it's important to keep these out of school experiences for the kids. Our field trips range from nature hikes, plays, museum trips and historical sites.
There are some kids who might never get to do these activities if it weren't for field trips!
